Massage ball



FIG. 1 is a front elevational view of a massage ball, showing my new design;

FIG. 2 is a left side elevational view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a rear elevational view thereof;

FIG. 7 is a perspective view thereof; and,

FIG. 8 is another perspective view thereof, with the broken line showing of the massaging unit being for illustrative purposes only and forming no part of the claimed design. 

The ornamental design for a massage ball, as shown and described. 